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gh-130230: Fix crash in pow() with only Decimal third argument (GH-130237)

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Serhiy Storchaka 2025-02-18 09:46:48 +02:00 • committed by GitHub
parent 4374e1de87
commit b93b7e566e
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3 changed files with 29 additions and 1 deletions
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9
Lib/test/test_decimal.py
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@ -4481,6 +4481,15 @@ class Coverage:
self.assertIs(Decimal("NaN").fma(7, 1).is_nan(), True)
# three arg power
self.assertEqual(pow(Decimal(10), 2, 7), 2)
if self.decimal == C:
self.assertEqual(pow(10, Decimal(2), 7), 2)
self.assertEqual(pow(10, 2, Decimal(7)), 2)
else:
# XXX: Three-arg power doesn't use __rpow__.
self.assertRaises(TypeError, pow, 10, Decimal(2), 7)
# XXX: There is no special method to dispatch on the
# third arg of three-arg power.
self.assertRaises(TypeError, pow, 10, 2, Decimal(7))
# exp
self.assertEqual(Decimal("1.01").exp(), 3)
# is_normal

1
Misc/NEWS.d/next/Library/2025-02-17-21-16-51.gh-issue-130230.9ta9P9.rst Normal file
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@ -0,0 +1 @@
Fix crash in :func:`pow` with only :class:`~decimal.Decimal` third argument.

20
Modules/_decimal/_decimal.c
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@ -147,6 +147,24 @@ find_state_left_or_right(PyObject *left, PyObject *right)
return (decimal_state *)state;
}
static inline decimal_state *
find_state_ternary(PyObject *left, PyObject *right, PyObject *modulus)
{
PyTypeObject *base;
if (PyType_GetBaseByToken(Py_TYPE(left), &dec_spec, &base) != 1) {
assert(!PyErr_Occurred());
if (PyType_GetBaseByToken(Py_TYPE(right), &dec_spec, &base) != 1) {
assert(!PyErr_Occurred());
PyType_GetBaseByToken(Py_TYPE(modulus), &dec_spec, &base);
}
}
assert(base != NULL);
void *state = _PyType_GetModuleState(base);
assert(state != NULL);
Py_DECREF(base);
return (decimal_state *)state;
}
#if !defined(MPD_VERSION_HEX) || MPD_VERSION_HEX < 0x02050000
#error "libmpdec version >= 2.5.0 required"
@ -4407,7 +4425,7 @@ nm_mpd_qpow(PyObject *base, PyObject *exp, PyObject *mod)
PyObject *context;
uint32_t status = 0;
decimal_state *state = find_state_left_or_right(base, exp);
decimal_state *state = find_state_ternary(base, exp, mod);
CURRENT_CONTEXT(state, context);
CONVERT_BINOP(&a, &b, base, exp, context);